Carbon has several different allotropes - materials made entirely out of carbon, that differ in their spatial structure, rendering different properties as well.
Two such allotropes are the Diamond and the Graphite.

The diamond's lattice is a variation on the FCC, having two inter-penetrating displaced FCC sub lattices. Each carbon is covalently bonded with 4 other neighbours
in the SP3 hybridization.

The carbon has a lattice consisting of stacked honeycombs planes. Bonds between coplanar atoms are covalent, and each atom has 3 neighbours. Bonding of different
layers is done by weak Van Der Waals bonds, making it easy to separate different layers.

Since SP3 bonds have higher energies compared to SP2 bonds, diamond is less stable than graphite, though in standard conditions conversions from diamonds to graphites are
negligible. This means, however, that transferring energy to a diamond might break the SP3 bonds, and with sufficient damage the crystal might, under annealing, reform as
a graphite. This result is well known and previously observed in laboratories and can be achieved by ion implantation, which creates a spherical damaged area, as can be seen
on the image to the left.

As previously mentioned, each carbon atom in a diamond has 4 neighbours, in an SP3 hybridization. This means all sites are occupied, and electrons are bound to the respective
atoms, making the diamond a great insulator. In contrary, carbon atoms in graphite have 3 neighbours, in an SP2 hybridization, allowing one free electron per atom to travel
between different sites. This makes graphite a conductor. It is a known fact that diamonds have a threshold in which their resistance drops, given a large enough concentration
of implanted ions. We can then deduce that if we use ion implantation to create overlapping graphitic spheres in the diamond, electrons would be able to percolate across the spheres
turning the diamond to a conductor. Indeed, observations reveal a threshold of ion concentration, after which the diamond model loses its insulator attributes.

My project aims to simulate and investigate the behaviour of a single damaged area in different scenarios - damages done by ion implantation, damages done by laser heating and the behaviour
of damaged areas with different spheres radii. In the future, it should include a simulation of several regions, investigating the percolation explanation to the diamond loosing its insulator
attributes.

Simulations are done in MD, using LAMMPS. This site would also, I hope, serve as a reference to other students starting to work with LAMMPS.

Previous results and simulations of graphitization can be found in the works of Dr. David Saada and Dr. Anastasia Sorkin.
For Dr. Sorkin's thesis on Computational Study of Structures of Diamonds and Amorphous Carbon Under Extreme Heating and Cooling, press here.
For Dr. Saada's dissertation on Comparison Between Tersoff Potential and Ab Initio Results for Surface Graphitization of Diamond, press here.